Technical Field

[0001] The present disclosure relates to the field of communication technologies, and in particular, to a configuration method for communication across multiple subbands in a carrier, between a base station (BS) and a user equipment (UE).

[0002] The communication technology is for example a 5G (fifth generation) network using the 5G NR (New Radio) as radio access technology (RAT) defined by 3GPP. The present disclosure is applicable to 5G NR-U (NR in unlicensed spectrum), but also to 5G NR (NR in licensed spectrum).

Background

[0003] According to the NR specification (see 3GPP TS 38.211 , Release 15.6.0), the UE detects the physical downlink control channel (PDCCH) via checking the PDCCH candidates within its corresponding control-resource set (CORESET) based on the control-channel element (CCE) index. While the concrete physical layer resources that each CCE index maps to should follow a specified relation which is different for interleaving and non-interleaving.

[0004] In NR specification, a CORESET (see section 7.3.2.2) consists of resource blocks in the frequency domain and symbols in the time domain. A control-channel element (CCE) consists of 6 resource-element groups (REGs) where a resource-element group equals one resource block during one orthogonal frequency-division multiplexing (OFDM) symbol. One REG has 12 consecutive subcarriers in the frequency domain and {1,2,3} OFDM symbols in the time domain. This definition sets the granularity for the CORESET. The REG index within the CORESET is defined with an order of time first and frequency second. The NR specification will group some of the REGs to form a REG bundle. One REG bundle can contain {2,3,6} REGs. The REG bundle index follows frequency domain. Examples of REG index naming in one CORESET and REG bundle containing 6 REGs are shown in Figure 1.

[0005] The CCE index to REG bundle index mapping relation depends on whether the interleaving is configured. For non-interleaving case, a fixed configuration, i.e. one REG bundle is composed of 6 REGs, is set by the specification and the mapping is that CCE index equals REG bundle index. While for the interleaving case, the CCE index to REG bundle index mapping needs to follow specified interleaving pattern (see section 7.3.2.2). Consequently, if a physical downlink control channel (PDCCH) candidate consisting of multiple CCEs is mapped to REG bundles spreading over the whole CORESET bandwidth, it yields better frequency selectivity.

[0006] In NR-U wide-band operation, BS and UE can operate in a wider band which consists of multiple subbands (SBs). As defined in NR specification, bandwidth part (BWP) is a subset of contiguous common resource blocks on a given carrier. Thus in the context of NR-U wide-band operation, a UE can be configured with an active BWP which contains multiple subbands, as shown in Figure 2A. However, by regulation, prior to each transmission in the SB, the sender (i.e. BS) needs to perform a Listen-before-Talk (LBT) procedure. This implies that for multiple SB transmissions, SB-based LBT has to be performed. Since the outcome of the multi-SB LBT cannot be uniform, partial transmission within the active BWP will become a common case as shown in Figure 2B.

[0007] Therefore, the question becomes how to design the CORESET to support such partial transmission case. One straightforward solution is to configure a CORESET dedicated to each SB as shown in Figure 3. Thus whatever SB LBT passes, the scheduling will be sent in the SB-specific CORESET. Although this design can naturally work, it has several limits, e.g. large number of CORESET per active BWP while the specification limits the number of CORESET per BWP. The current limit is 3, hinting to support only 3 SBs.

[0008] Another solution is to design a CORESET that covers multiple SBs as shown in Figure 4. However, due to the fact that the interleaving pattern will make one PDCCH candidate spreading over all the CORESET bandwidth, the potential risk is that some part of the PDCCH will be punctured due to certain SB LBT-failure. As a consequence, the PDCCH robustness will be reduced.

[0009] The SB-based interleaving can avoid the PDCCH puncturing due to SB- LBT failure, but at the same time, it reduces the frequency selectivity. The challenge is to define a more flexible design which can render a good compromise between PDCCH puncture risk and frequency selectivity gain. Summary

[0010] A first object of the present disclosure is a configuration method for transmission across multiple subbands in a carrier, performed in a base station (BS), the configuration method comprising:

- configuring a plurality of chunks corresponding to a control resource set

(CORESET) including a plurality of resource element groups (REGs) and partially overlapping with the multiple subbands, each chunk overlapping with a part of the CORESET within one or several subbands;

- configuring a control channel consisting of one or more control-channel elements (CCEs) and setting an interleaved CCE-to-REG mapping for each chunk;

- performing a listen before talk (LBT) procedure over each subband;

- selecting the available subbands for transmission;

- adapting the plurality of chunks to a reduced member of chunks that fully overlaps the CORESET in the available subbands.

[0011] Such configuration method, with the introduction of chunks overlapping with parts of the CORESET within one or several subbands, defines a more flexible design giving a good compromise between the PDCCH frequency selectivity and the risk of PDCCH puncturing due to LBT failure happened in certain subbands. By a reduced number of chunks, it is meant a number of chunks that is strictly lower than the number of chunks contained in the plurality of chunks corresponding to the control resource set.

[0012] The configuration step of a plurality of chunks can be split into:

- configuring a control resource set (CORESET) including a plurality of resource element groups (REGs) and partially overlapping with the multiple subbands;

- configuring a plurality of chunks corresponding to the CORESET, each chunk overlapping with a part of the CORESET within one or several subbands. [0013] Advantageously, the configuration method is further comprising:

- performing the setting of an interleaved CCE-to-REG mapping for each chunk with a flexible starting CCE index.

[0014] Such configuration method provides a generic design of the interleaved CCE-to-REG mapping which can be flexibly adapted according to the available wideband width.

[0015] Advantageously, the starting CCE index for each chunk is given by i ^start , where , wherei ^start is a non-negative integer and is the total number of CCEs in the configured CORESET.

[0016] Advantageously, the interleaved CCE-to-REG mapping within a chunk is given by:

- REG bundle i is defined as REGs {iL,iL+1,...,iL+L-1} where L is the REG bundle size,

- CCE index j consisting of REG bundles {ƒ(6j/L)ƒ(6j/L 1),...,ƒ(6j/L+6/L-1)}

- where the CCE index j should be within the range of is the total number of CCEs in one chunk, and is the number of REGs within said overlapped part of the CORESET within said one or several subbands.

[0017] Such introduction of a chunk allows to keep the current control channel configuration and to cope with the impact of partial BWP transmission.

[0018] Advantageously, the configuration method is further comprising before adapting the plurality of chunks to a reduced number of chunks, the steps of :

- transmitting, to a user equipment, the available subbands for transmission through the control channel; and

- waiting a predetermined timeframe.

[0019] Advantageously, the configuration method is further comprising before adapting the plurality of chunks to a reduced number of chunks, the steps of :

- transmitting, to a user equipment, the available subbands for transmission through the control channel; and

- transmitting control information to inform the user equipment to trigger the chunk adaptation through the control channel.

[0020] Advantageously, the configuration method is further comprising before adapting the plurality of chunks to a reduced number of chunks, the steps of :

- transmitting control information to inform the user equipment to trigger the chunk adaptation through the control channel.

[0021] Advantageously, the control channel includes a group common physical downlink control channel (GC-PDCCH) and/or a UE-specific downlink control information (UE-specific DCI).

[0022] Such configuration method gives a mechanism so that UE can detect base station transmission across multiple carriers and/or multiple LBT bandwidths in a carrier, by explicit indication via the control channel, either the group common PDCCH or the UE-specific DCI.

[0023] Advantageously, the reduced number of chunks is one chunk.

[0024] A second object of the present disclosure is a configuration method for reception across multiple subbands in a carrier performed in a user equipment, the configuration method comprising: - configuring a plurality of chunks corresponding to a control resource set

(CORESET) including a plurality of resource element groups (REGs) and partially overlapping with the multiple subbands, each chunk overlapping with a part of the CORESET within one or several subbands;

- receiving configuration of a control channel consisting of one or more control- channel elements (CCEs) and setting an interleaved CCE-to-REG mapping for each chunk;

- receiving the available subbands for transmission;

- switching the plurality of chunks to a reduced number of chunks that fully overlaps the CORESET in the available subbands. [0025] Such configuration method allows the UE to switch the interleaving pattern within the BS initiated channel occupancy time (COT) in a wideband operation.

[0026] The configuration step of a plurality of chunks can be split into:

- configuring a control resource set (CORESET) including a plurality of resource element groups (REGs) and partially overlapping with the multiple subbands;

- configuring a plurality of chunks corresponding to the CORESET, each chunk overlapping with a part of the CORESET within one or several subbands. [0027] Alternatively, the user equipment may receive from the base station a configuration of a CORESET and/or a configuration of a plurality of chunks. [0028] Advantageously, the setting of an interleaved CCE-to-REG mapping for each chunk is performed with a flexible starting CCE index.

[0029] Advantageously, the configuration method is further comprising before switching the plurality of chunks to a reduced number of chunks, the steps of :

- receiving, from a base station, the available subbands for transmission through the control channel; and

- waiting a predetermined timeframe.

[0030] Advantageously, the configuration method is further comprising before switching the plurality of chunks to a reduced number of chunks, the steps of :

- receiving, from a base station, the available subbands for transmission through the control channel; and

- receiving, from the base station, control information to trigger the chunk switch through the control channel.

[0031] Advantageously, the configuration method is further comprising before switching the plurality of chunks to a reduced number of chunks, the steps of :

- receiving, from a base station, control information to trigger the chunk switch through the control channel.

[0032] Advantageously, the control channel includes a ground common physical downlink control channel (GC-PDCCH) and/or a UE-specific downlink control information.

[0033] Advantageously, the reduced number of chunks is one chunk.

[0034] A third object of the present disclosure is a base station in a mobile telecommunication network, comprising a module for connecting a user equipment to the mobile telecommunication system, configured to control the execution of the configuration method for transmission across multiple subbands defined in the first object.

[0035] A fourth object of the present disclosure is a user equipment comprising a module for connecting to a mobile telecommunication system, configured to control the execution of the configuration method for reception across multiple subbands defined in the second object.

[0036] A fifth object of the present disclosure is a computer readable medium comprising program instructions for causing a user equipment to perform the steps of a method according to the second object.

[0037] A sixth object of the present disclosure is a computer readable medium comprising program instructions for causing a base station to perform the steps of a method according to the first object.

Brief description of the drawings

[0038] The appended drawings required in description of embodiments or the prior art will be briefly described below.

- Fig. 1 shows examples of REG index naming in one CORESET and REG bundle containing 6 REGs;

- Fig. 2A shows a configuration with an active BWP which contains multiple subbands and Fig. 2B shows a partial transmission within the active BWP;

- Fig. 3 shows a configuration where a CORESET is dedicated to each SB;

- Fig. 4 shows a configuration where a CORESET covers multiple SBs;

- Fig. 5A shows a configuration of a plurality of chunks corresponding to a

CORESET, each chunk overlapping with a part of the CORESET within one or several subbands;

- Fig. 5B shows another configuration of a plurality of chunks corresponding to a

CORESET, each chunk overlapping with a part of the CORESET within one or several subbands;

- Fig. 6 shows an example of a plurality of chunks and the corresponding starting

CCE index;

- Fig. 7A shows an active BWP which contains 4 subbands and a configured

CORESET which is partially overlapped with all subbands;

- Fig. 7B shows a setting of 4 chunks, each chunk overlapping with the part of the

CORESET within each subband;

- Fig. 7C shows the chunk adaptation / switch to one chunk that fully overlaps the

CORESET in all available subbands.

Description of embodiments

[0039] In the following disclosure, we present a configuration method for transmission across multiple subbands in a carrier on the base station side and a configuration method for reception across multiple subbands in a carrier on the user equipment side, both configuration methods being based on a generic design of the interleaved CCE-to-REG mapping which can be flexibly adapted/switched according to the available wideband width. We also present a mechanism for enabling such adaptation/switch.

[0040] Generic interleaved mapping method

[0041] In NR specification, the CCE-to-REG bundle interleaving can be expressed as follows (see section 7.3.2.2):

- CCE j consists of REG bundles {ƒ(6j/L),ƒ(6j/L 1\...,ƒ(6j/L+6/L-1)} where ƒ(·)

- The interleaver is defined by where the variable stands for the number of REGs in CORESET. C and R stand for the interleaving depth.

[0042] In our new design of interleaving pattern, we introduce a new variable which stands for the number of REGs within one or several parts of the CORESET called chunk.

[0043] Fig. 5A shows a configuration of a plurality of chunks corresponding to a CORESET, each chunk overlapping with a part of the CORESET within one or several subbands. In this example, one CORESET 1 is spread over 2 subbands SB1 and SB2 and two chunks (1 and 2) are introduced, each chunk overlapping a part of the CORESET in each subband.

[0044] Note that this is one possible example, 1 chunk can also be configured to overlap several parts of the CORESET 1 in a plurality of subbands. Fig. 5B shows another configuration of a plurality of chunks corresponding to a CORESET, each chunk overlapping with a part of the CORESET within one or several subbands. In this example, CORESET 1 is spread over 4 subbands SB1 -SB4. 3 chunks (CHUNK1 , CHUNK2 and CHUNK3) are introduced. CHUNK 1 overlaps a part of CORESET 1 in two subbands SB1 and SB3. CHUNK2 overlaps a part of CORESET 1 in subband SB2 and CHUNK3 overlaps a part of CORESET 1 in subband SB4.

[0045] In NR specification, one CORESET is corresponding to a unique “chunk”, with a starting CCE index being zero. In our new design of interleaving pattern, a second variable is advantageously introduced, that is a starting CCE index for each chunk which can be set flexibly, i.e. i ^start , where , where i ^start is a non-negative integer and is the total number of CCEs in a CORESET. In order to visualize how the starting CCE index can be flexibly set, Figure 6 shows an example of a plurality of chunks corresponding to one CORESET where:

- Chunk 1 starts with a CCE index of zero;

- Chunk 2 starts with a CCE index of 1 ;

- Chunk 3 starts with a CCE index of 3; and

- Chunk 4 starts with a CCE index of 5; i.e. the CCE index can be flexibly set so as to correspond to the REG bundle(s) of the CORESET it contains.

[0046] Thus a new interleaved CCE-to-REG bundle mapping within a chunk is given by:

- CCE index j consists of REG bundles {ƒ(6j/L),ƒ(6j/L 1),...,ƒ(6j/L+6/L-1)} where

[0047] Here, we stress that the CCE index j should be within the range of is the total number of CCEs in 1 chunk. This can be also obtained by

[0048] In the following disclosure, 3 examples are described assuming that a UE is configured with an active BWP which contains 4 subbands. Moreover, the configured CORESET is partially overlapped with all subbands (SB1-SB4) as shown in Figure 7a. We further assume that the UE is connected to the network (in the connected mode) and its PDCCH configuration sets CCE-to-REG as interleaved. [0049] Example 1

[0050] From the BS side: [0051] Prior to the transmission, the BS performs LBT individually for each of the SBs (SB1-SB4). According to the LBT outcomes, the BS will select the available subbands for the transmission. At the same time, the BS will set 4 chunks (chunk 1 to 4), each chunk overlaps with the part of the CORESET within each subband as shown in Figure 7B.

[0052] Then, the BS will prepare a control channel signal, i.e. the group- common PDCCH in which the BS will indicate the SB LBT outcomes. For instance, if only SB2 does not pass LBT, GC-PDCCH will use 4-bit bitmap (1011) to indicate that SB 1 ,3,4 are available for transmission. Once the BS has sent the GC-PDCCH, it will wait a predefined time frame (time t), then the BS will adapt the number of the chunks to one that fully overlaps the CORESET in all available subbands as shown in Figure 7C.

[0053] From the UE side:

[0054] When the UE does not detect GC-PDCCH, it sets the number of the chunks to 4, each chunk overlaps with the partial CORESET in each subband. Once the UE detects the GC-PDCCH and it reads the bitmap indicating the available SBs. The UE will switch the chunk number to 1 which fully overlaps the CORESET in all available subbands, after a predefined time frame.

[0055] Example 2

[0056] From the BS side:

[0057] Prior to transmission, the BS performs LBT individually for each of the SBs (SB1-SB4), according to the LBT outcomes, the BS will select the available subbands for the transmission. At the same time, the BS will set 4 chunks, each overlaps with the part of the CORESET within each subband as example 1 as shown in Figure 7B.

[0058] Then, the BS will prepare the group-common PDCCH in which the BS will indicate the SB LBT outcomes. For instance, if only SB2 does not pass LBT, GC- PDCCH will use 4-bit bitmap (1011) to indicate that SB 1 ,3,4 are available for transmission. BS sends an UE-specific DCI to inform the UE to trigger the chunk change. The chunk change should be indicated together with the GC-PDCCH previously transmitted, i.e. BS will adapt the number of the chunks to one that fully overlaps the CORESET in all available subbands. The BS may expect (or not) the ACK/NACK from the UE. The BS will implement the new chunk change after it receives the ACK/NACK (or not) as shown in Figure 7C. [0059] From the UE side:

[0060] When the UE does not detect GC-PDCCH, it sets the number of the chunks to 4, each overlaps with the partial CORESET in each subband. Once the UE detects the GC-PDCCH and it reads the bitmap indicating the available SBs. The UE might expect a UE-specific DCI to trigger the chunk change. Once received, the UE might need to feedback the ACK/NACK before switching the chunk number to 1 which fully overlaps the CORESET in all available subbands.

[0061] Example 3

[0062] From the BS side: [0063] Prior to transmission, the BS performs LBT individually for each of the

SB, according to the LBT outcomes, the BS will select the available subbands for the transmission. At the same time, the BS will set 4 chunks, each overlaps with the part of the CORESET within each subband as shown in Figure 7B.

[0064] Then the BS will send a UE-specific DCI to the UE to inform about the chunk change, in which, the BS indicates the new number of Chunks and the starting CCE index of each chunk. The BS expects the ACK/NACK (or not) from the UE. The BS will implement the new chunk change after it receives the ACK/NACK (or not) as shown in Figure 7C.

[0065] From the UE side: [0066] When the UE does not detect UE-specific chunk change request, it sets the number of the chunks to 4, each overlaps with the partial CORESET in each subband. Once the UE detects the UE-specific chunk change request, the UE might need to feedback the ACK/NACK before switching the newly configured chunks. [0067] Although in the above examples 1-3, the BS adapts the plurality of chunks to one and respectively the UE switches the plurality of chunks to one, it is understood that the BS may adapt the plurality of chunks to a reduced number of chunks, respectively the UE may switch the plurality of chunks to a reduced number of chunks.

[0068] List of abbreviations in the description and drawings:

[0069] In the above description, the mobile telecommunication system is a 5G mobile network comprising a 5G NR access network. The present example embodiment is applicable to NR in unlicensed spectrum (NR-U) and also to NR in licensed spectrum (NR). The present disclosure can be applied to other mobile networks, in particular to mobile network of any further generation cellular network technology (6G, etc.).

[0070] The above is only a specific implementation manner of the present disclosure, the protection scope of the present disclosure is not limited thereto, and changes or substitutions that can easily be thought of by those skilled in the art within the technical scope disclosed in the present disclosure should be covered by the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

The various embodiments / examples, aspects and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the disclosure.